Defining the intrapartition data set

You can either use the sample job described here to define the transient data intrapartition data set, or you can use the CICS-supplied job, DFHDEFDS. DFHDEFDS creates the DFHINTRA data set as one of the data sets for a CICS region

About this task

The intrapartition data set must be big enough to hold all the data for intrapartition queues. If you are using the sample job to define the transient data intrapartition data set, perform the following steps:

Procedure

  1. Decide if a single extent data set on a single volume is appropriate.
    If you define one extent on one volume, you might require a much larger data set than your average requirements to cater for exceptional cases. You can define multiple extents or multiple volumes or both for the data set. For details, see Using multiple extents and multiple volumes.
  2. Specify a CONTROLINTERVALSIZE parameter that is large enough to hold the longest data record, in addition to the 32 bytes that CICS requires for its own purposes. The maximum control interval size is 32 KB.
    Space is allocated to queues in units of a control interval (CI). The first CI is reserved for CICS use; the remaining CIs are available to hold data. Data records are stored in CIs according to VSAM standards.
  3. If you allocate space in records, rather than tracks or cylinders, you must specify a RECORDSIZE value.
    The value must be 7 bytes less than the CONTROLINTERVALSIZE.
  4. Add the data definition statement for the intrapartition data set to the CICS startup job stream.
    The DD name for the intrapartition data set is DFHINTRA, and the DSN operand must be the name of the VSAM entry-sequenced data set. For example, you could specify:
    //DFHINTRA  DD  DSNAME=CICSTS52.CICS.applid.DFHINTRA,DISP={OLD|SHR}

Example

Figure 1. Sample job to define a transient data intrapartition data set
//DEFDS     JOB  accounting info,name,MSGCLASS=A
//TDINTRA   EXEC PGM=IDCAMS
//SYSPRINT  DD   SYSOUT=A
//SYSIN     DD   *
       DEFINE CLUSTER -
                ( NAME(CICSTS52.CICS.applid.DFHINTRA)    -
                  RECORDSIZE(1529,1529)            -
                  RECORDS(100)                     -
                  NONINDEXED                       -
                  CONTROLINTERVALSIZE(1536)        -
                  VOL(volid))                      -
              DATA  -
                ( NAME(CICSTS52.CICS.applid.DATA.DFHINTRA))
/*
//

What to do next

Use the TD system initialization parameter to specify an appropriate number of VSAM buffers and strings for the transient data intrapartition data set. CICS uses buffers to make control intervals from the data set available in CICS storage, and uses strings for VSAM I/O requests between a buffer and the data set. Typically, the default setting of three buffers and three strings is sufficient.